Development and Evaluation of Multistructured and Hierarchical Epidermal Growth Factor-Poly ( ε -Caprolactone) Scaffolds

Electrospinning/3D printing drug-loaded antibacterial polycaprolactone nanofiber/sodium alginate-gelatin hydrogel bilayer scaffold for skin wound repair

Skin injuries and defects, as a common clinical issue, still cannot be perfectly repaired at present, particularly large-scale and infected skin defects. Therefore, in this work, a drug-loaded bilayer skin scaffold was developed for repairing full-thickness skin defects. Briefly, amoxicillin (AMX) was loaded on polycaprolactone (PCL) nanofiber via electrospinning to form the antibacterial nanofiber membrane (PCL-AMX) as the outer layer of scaffold to mimic epidermis. To maintain wound wettability and promote wound healing, external human epidermal growth factor (rhEGF) was loaded in sodium alginate-gelatin to form the hydrogel structure (SG-rhEGF) via 3D printing as inner layer of scaffold to mimic dermis. AMX and rhEGF were successfully loaded into the scaffold. The scaffold exhibited excellent physicochemical properties, with elongation at break and tensile modulus were 102.09 ± 6.74% and 206.83 ± 32.10 kPa, respectively; the outer layer was hydrophobic (WCA was 112.09 ± 4.67°), while the inner layer was hydrophilic (WCA was 48.87 ± 5.52°). Meanwhile, the scaffold showed excellent drug release and antibacterial characteristics. In vitro and in vivo studies indicated that the fabricated scaffold could enhance cell adhesion and proliferation, and promote skin wound healing, with favorable biocompatibility and great potential for skin regeneration and clinical application.

Controlling cell elongation and orientation by using microstructural nanofibre scaffolds for accelerating tissue regeneration

The topographic surface conditions of scaffolds can regulate cellular behaviours, such as by stimulating cellular migration and morphological changes to wound sites and have the potential to promote tissue regeneration. In this research, four types of engineered topographic surfaces, including arrays of hemisphere, pyramid, semi-cylinder, and triangle prism microstructures, were patterned on silicon moulds using microfabrication processes. The microstructural patterns were transferred onto the surface of polycaprolactone membranes and nanofibrous scaffolds by combining with the moulding approach and electrospinning technique, respectively. In vitro experimental results demonstrated that the triangular microstructural nanofibre provided a strong guiding performance to the filopodia of cultured C2C12 myoblast cells, thus inducing cellular elongation and alignment in the longitudinal direction and forming an elongated cell morphology. The cultured cells rapidly transitioned into an elongated morphology at an aspect ratio of 17.33 after 24 h of incubation, with 70% of the cell elongates aligning with the direction of triangular microstructural patterns. The cells cultured on the triangular microstructural nanofibre elongated four-fold compared with those in the flat nanofibre scaffold. Moreover, an in vivo study showed that wounds treated with the triangular microstructural nanofibre scaffold achieved 95.04% wound closure after 14 days and completed the reepithelialisation with an ordered collagen arrangement. Therefore, we believe that the engineered triangular nanofibrous scaffold may accelerate tissue regeneration and has potential for wound healing applications.

Growth Factors, Reactive Oxygen Species, and Metformin-Promoters of the Wound Healing Process in Burns?

Burns can be caused by various factors and have an increased risk of infection that can seriously delay the wound healing process. Chronic wounds caused by burns represent a major health problem. Wound healing is a complex process, orchestrated by cytokines, growth factors, prostaglandins, free radicals, clotting factors, and nitric oxide. Growth factors released during this process are involved in cell growth, proliferation, migration, and differentiation. Reactive oxygen species are released in acute and chronic burn injuries and play key roles in healing and regeneration. The main aim of this review is to present the roles of growth factors, reactive oxygen species, and metformin in the healing process of burn injuries.

Micropatterned Fibrous Scaffold Produced by Using Template-Assisted Electrospinning Technique for Wound Healing Application

This paper describes the fabrication of a structural scaffold consisting of both randomly oriented nanofibers and triangular prism patterns on the scaffold surface using a combination technique of electrospinning and collector templates. The polycaprolactone (PCL) nanofibers were electrospun over a triangular prism pattern mold, which acted as a template. The deposited scaffold was removed from the template to produce a standalone structural scaffold of three-dimensional micropatterned nanofibers. The fabricated structural scaffold was compared with flat randomly oriented nanofibers based on in vitro and in vivo studies. The in vitro study indicated that the structural scaffold demonstrated higher fibroblast cell proliferation, cell elongation with a 13.48 ± 2.73 aspect ratio and 70% fibroblast cell orientation compared with flat random nanofibers. Among the treatment groups, the structural scaffold escalated the wound closure to 92.17% on day 14. Histological staining of the healed wound area demonstrated that the structural scaffold exhibited advanced epithelization of the epidermal layer accompanied by mild inflammation. The proliferated fibroblast cells and collagen fibers in the structural scaffold appeared denser and arranged more horizontally. These results determined the potential of micropatterned scaffolds for stimulating cell behavior and their application for wound healing.

Epithelial Growth Factor-Anchored on Polycaprolactone/6-deoxy-6-amino-β-cyclodextrin Nanofibers: In Vitro and In Vivo Evaluation

Polycaprolactone (PCL) is a well-known FDA approved biomaterial for tissue engineering. However, its hydrophobic properties limit its use for skin wound healing which makes its functionalization necessary. In this work, we present the fabrication and evaluation of PCL nanofibers by the electrospinning technique, as well as PCL functionalized with 6-deoxy-6-amino-β-cyclodextrin (aminated nanofibers). Afterwards, epithelial growth factor (EGF) was anchored onto hydrophilic PCL/deoxy-6-amino-β-cyclodextrin. The characterization of the three electrospun fibers was made by means of field emission scanning electron microscopy (FESEM), Fourier transform infrared spectroscopy-attenuated total reflectance (FTIR-ATR); Confocal-Raman Spectroscopy were used for elucidated the chemical structure, the hydrophilicity was determined by Contact Angle (CA). In vitro cell proliferation test was made by seeding embryonic fibroblast cell line (3T3) onto the electrospun mats and in vivo studies in a murine model were conducted to prove its effectivity as skin wound healing material. The in vitro studies showed that aminated nanofibers without and with EGF had 100 and 150% more cell proliferation of 3T3 cells against the PCL alone, respectively. In vivo results showed that skin wound healing in a murine model was accelerated by the incorporation of the EGF. In addition, the EGF had favorable effects in epidermal cell proliferation. The study demonstrates that a protein of high biological interest like EGF can be attached covalently to the surface of a synthetic material enriched with amino groups. This kind of biomaterial has a great potential for applications in skin regeneration and wound healing.

Epidermal and fibroblast growth factors incorporated polyvinyl alcohol electrospun nanofibers as biological dressing scaffold

In this study, single, mix, multilayer Polyvinyl alcohol (PVA) electrospun nanofibers with epidermal growth factor (EGF) and fibroblast growth factor (FGF) were fabricated and characterized as a biological wound dressing scaffolds. The biological activities of the synthesized scaffolds have been verified by in vitro and in vivo studies. The chemical composition finding showed that the identified functional units within the produced nanofibers (O-H and N-H bonds) are attributed to both growth factors (GFs) in the PVA nanofiber membranes. Electrospun nanofibers' morphological features showed long protrusion and smooth morphology without beads and sprayed with an average range of 198-286 nm fiber diameter. The fiber diameters decrement and the improvement in wettability and surface roughness were recorded after GFs incorporated within the PVA Nanofibers, which indicated potential good adoption as biological dressing scaffolds due to the identified mechanical properties (Young's modulus) in between 18 and 20 MPa. The MTT assay indicated that the growth factor release from the PVA nanofibers has stimulated cell proliferation and promoted cell viability. In the cell attachment study, the GFs incorporated PVA nanofibers stimulated cell proliferation and adhered better than the PVA control sample and presented no cytotoxic effect. The in vivo studies showed that compared to the control and single PVA-GFs nanofiber, the mix and multilayer scaffolds gave a much more wound reduction at day 7 with better wound repair at day 14-21, which indicated to enhancing tissue regeneration, thus, could be a projected as a suitable burn wound dressing scaffold.

Nonwoven membranes for tissue engineering: an overview of cartilage, epithelium, and bone regeneration

Scaffold-type biomaterials are crucial for application in tissue engineering. Among them, the use of a nonwoven scaffold has grown in recent years and has been widely investigated for the regeneration of different types of tissues. Several polymers, whether they are synthetic, biopolymers or both, have been used to produce a scaffold that can mimic the natural tissue to which it will be applied to. The scaffolds used in tissue engineering must be biocompatible and allow cell adhesion and proliferation to be applied in tissue engineering. In addition, the scaffolds should maintain the mechanical properties and architecture of the desired tissue. Nonwoven fabrics have produced good results and are more extensively applied for the regeneration of cartilage, epithelial and bone tissues. Recent advances in tissue engineering have shown promising results, however, no ideal material or standardization parameters and characteristics of the materials were obtained. The present review provides an overview of the application of nonwoven scaffolds, including the main results obtained regarding the properties of the biomaterials and their applications in vitro and in vivo, focusing on the cartilaginous, the epithelium, and bone tissue regeneration.